Dental implant with interlocking and centering threads

ABSTRACT

A dental implant device for insertion into a bore defined in bone for use with a prosthetic tooth or dental appliance includes an abutment with a plurality of male keys disposed about the distal end of the abutment capable of being affixed to the prosthetic tooth or dental appliance, an implantable anchor having a proximal and distal end, a plurality of female keyways defined into the proximal end of the anchor, the keyways capable of coupling to the male keys of the abutment and thereby preventing relative rotation of the abutment and anchor; an interlocking thread helically defined around a longitudinal axis of the anchor, the thread being adapted to couple to the bore defined in the bone and means for coupling the abutment to the implant anchor.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuing application of prior application Ser. No.12/489,274 filed on Jun. 22, 2009, pursuant to 35 U.S.C. §§120 and 121,and hereby incorporates that application by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to dental implant and more particularlyto a dental implant anchoring device with threading which does notcompress or exert expanding pressure to the surrounding bone.

2. Description of the Prior Art

Dental implants have been used as artificial tooth roots on whichprosthetic teeth are mounted. A conventional dental implant 1 shown inFIG. 1 has been described in U.S. Pat. No. 7,198,488. The dental implant1 has a cylindrical anchoring head 2 formed unitarily with a screwelement 3. The screw element 3, usually made of titanium with aroughened surface, is to be screwed into the recipient jaw bone. Theanchoring head 2 is adapted to have a prosthetic tooth mounted on it.

The screw element 3 has a thread core 8 and a self-cutting externalthread 9. After being anchored into the bone, it may take months for newbone to grow into close proximity with the surface of the screw element3. Because of a unique property of roughened titanium, newly grown bonecan adhere tightly to the surface of the screw element 3.

BRIEF SUMMARY OF THE INVENTION

An illustrated embodiment of the invention is a dental implant devicefor insertion into bone, comprising an implant anchor having aninterlocking thread helically defined around a longitudinal axis. Thethread is adapted to couple to a female threaded bore in the bone.

The dental implant device for insertion into a bore defined in bone foruse with a prosthetic tooth or dental appliance, comprising an abutmentwith a plurality of male keys disposed about the distal end of theabutment, which distal end is capable of being affixed to the prosthetictooth or dental appliance; an implantable anchor having a proximal anddistal end, a plurality of female keyways defined into the proximal endof the anchor, the keyways capable of coupling to the male keys of theabutment and thereby preventing relative rotation of the abutment andanchor; an interlocking thread helically defined around a longitudinalaxis of the anchor, the thread being adapted to couple to the boredefined in the bone; and means for coupling the abutment to the implantanchor.

In another embodiment, the dental implant device further comprises arepository bore perpendicular to the longitudinal bore defined in adistal portion of the anchor. The repository bore is cut through thethreaded portion of the anchor creating very sharp cutting edges on theface of each thread to allow the threads to become self tapping. Therepository bore also serves as a repository for the bone chips createdduring the thread cutting process. This allows the chips to be movedinto and contained within the repository bore preventing galling,interference and radial forces during the thread cutting process. Thisproduces clean cut threads similar to those cut with a tap unlike theincomplete threads cut by the crude and dull edges of prior self tappingdevices.

The repository bore of the dental implant comprises a bore definedtransversely into the anchor and having an elliptical shape.

The abutment of the dental implant device has a corresponding centrallongitudinal bore defined through its respective longitudinal axis, andwhere the anchor has a central longitudinal bore defined at leastpartially through its respective longitudinal axis.

The central bore defined through the longitudinal axis of the abutmentcomprises a clearance bore with an inner smooth surface.

In another embodiment, the central bore defined through the longitudinalaxis of the anchor comprises a threaded blind bore with an inner femalethreaded surface.

In yet another embodiment, the means for coupling the abutment to theanchor comprises a threaded bolt configured to be disposed into thecentral hollow bores defined through the longitudinal axis of theabutment and the anchor.

The threaded bolt is adapted to threadably engage the inner femalethreaded surface of the anchor.

In another embodiment, the bolt has a head and where the abutment has arecessed proximal flanged surface and is adapted to receive the head ofthe threaded bolt in the recessed proximal flanged surface.

In still another embodiment, the means for coupling the abutment to theanchor further comprises means for locking the male keys disposed on thedistal end of the abutment into the female keyways disposed on theproximal end of the implant anchor.

In a separate illustrated embodiment a dental implantable device isprovided for insertion into bone for use with a prosthetic toothcomprising: an abutment with a plurality of male keys disposedsymmetrically about the distal end of the abutment, the prosthetic toothcoupled to the abutment; an implantable anchor with a proximal anddistal end and having a plurality of female keyways disposedsymmetrically about the proximate end of the implantable anchor capableof coupling to the male keys of the abutment and an interlocking threadhelically defined around a longitudinal axis, the thread being adaptedto thread into a bore in the bone; means for coupling the abutment tothe implantable anchor; and a self-tapping flute defined in a distalportion of the implantable anchor.

In another embodiment, the abutment and implantable anchor each have acorresponding central hollow bore defined along their respectivelongitudinal axes.

In another embodiment, the means for coupling the abutment to theimplantable anchor comprises a threaded bolt arranged and configured tofit through the corresponding central hollow bores defined through thelongitudinal axis of the abutment and to thread into the correspondingcentral hollow bores defined through the longitudinal axis of theimplantable anchor.

In yet another embodiment, the means for coupling the abutment to theimplantable anchor comprises means for maintaining the male keysdisposed on the distal end of the abutment angularly fixed relative tothe female keyways disposed on the proximal end of the implantableanchor.

The illustrated embodiment also includes a method of implanting a dentalimplant into a female threaded portion of bone comprising the steps ofself-tapping a male threaded portion of an implantable anchor into abore defined in bone using a chip repository bore defined in theimplantable anchor; tightening the implantable anchor into the boredefined in the bone, wherein tightening the implantable anchor comprisescreating a radially interlocking and centering force between the malethreaded portion of the implantable anchor and the female threadedportion of the bone; and coupling an abutment to the implantable anchorwhile preventing relative rotation of the abutment with respect to theimplantable anchor.

The method further includes where coupling the abutment to theimplantable anchor comprises interlocking a plurality of male keysdisposed on the distal end of the abutment to a matching plurality offemale keyways defined into the proximal end of the implantable anchor.

In another embodiment, the method step of where coupling the abutment tothe implantable anchor comprises inserting a threaded bolt through adefined hollow bore defined along the longitudinal axis of the abutmentand the implantable anchor, which bolt maintains at least one keydefined on either the abutment or the anchor into a keyway defined intothe other one of either the abutment or the anchor.

The embodiment further comprises coupling the threaded bolt with aninner female threaded surface of the implantable anchor and threadingthe threaded bolt until the bolt head of the threaded bolt contacts aninner recessed flange defined in the abutment.

Finally, in a last embodiment, the method step where coupling theabutment to the implantable anchor further comprises inserting athreaded bolt through a defined hollow bore along the longitudinal axisof the abutment and the implantable anchor; coupling the threaded boltwith an inner female threaded bore of the implantable anchor; andthreading the threaded bolt until a bolt head of the threaded boltcontacts an inner recessed flange defined in the abutment.

While the apparatus and method has or will be described for the sake ofgrammatical fluidity with functional explanations, it is to be expresslyunderstood that the claims, unless expressly formulated under 35 USC112, are not to be construed as necessarily limited in any way by theconstruction of “means” or “steps” limitations, but are to be accordedthe full scope of the meaning and equivalents of the definition providedby the claims under the judicial doctrine of equivalents, and in thecase where the claims are expressly formulated under 35 USC 112 are tobe accorded full statutory equivalents under 35 USC 112. The inventioncan be better visualized by turning now to the following drawingswherein like elements are referenced by like numerals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side cross-sectional view which shows a conventional dentalimplant.

FIG. 2 a is an exploded side cross-sectional view which shows componentsof a dental implant device in accordance with an embodiment of theinvention employing a threaded collar and an internally thread abutment.

FIG. 2 b is a top plan view of the abutment shown in the exploded viewof FIG. 2 a as seen from section lines 2 b-2 b in FIG. 2 a.

FIG. 2 c is a top plan view of the collar shown in the exploded view ofFIG. 2 a as seen from section lines 2 c-2 c in FIG. 2 a.

FIG. 2 d is a top plan view of the anchor shown in the exploded view ofFIG. 2 a as seen from section lines 2 d-2 d in FIG. 2 a.

FIG. 3 is a side view of the distal portion of the anchor in enlargedscale which shows a threaded section of the dental implant of theinvention, which a lower right partially cut-away side cross-sectionalportion.

FIG. 4 is a side cross-sectional view of a bone site which shows afemale threaded section for receiving the dental implant.

FIG. 5 is a side view of the distal portion of the anchor in enlargedscale which illustrates the reaction forces from the bone applied to thethreaded section of the dental implant with a partially cut-away sectionof the anchor shown in side cross-sectional view coupled to the femalethreaded section in the bone site as shown in side cross-sectional view.

FIG. 6 is a side view of the assembled device of FIG. 2 a.

FIG. 7 a is an exploded side cross-sectional view of a second embodimentwhich shows a dental implant device having an adjustable unthreadedcollar and an internally thread abutment.

FIG. 7 b is a top plan view of the shoulder shown in the exploded viewof FIG. 7 a as seen from section lines 7 b-7 b in FIG. 7 a.

FIG. 7 c is a top plan view of the collar shown in the exploded view ofFIG. 7 a as seen from section lines 7 c-7 c in FIG. 7 a.

FIG. 7 d is a top plan view of the anchor shown in the exploded view ofFIG. 7 a as seen from section lines 7 d-7 d in FIG. 7 a.

FIG. 8 is an assembled side elevational view of the embodiment of FIG. 7a.

FIG. 9 a is an exploded side cross-sectional view of a third embodimentwhich shows a dental implant device having an adjustable unthreadedcollar and an externally threaded shaft extending distally from theabutment.

FIG. 9 b is a top plan view of the shoulder shown in the exploded viewof FIG. 9 a as seen from section lines 9 b-9 b in FIG. 9 a.

FIG. 9 c is a top plan view of the collar shown in the exploded view ofFIG. 9 a as seen from section lines 9 c-9 c in FIG. 9 a.

FIG. 9 d is a top plan view of the anchor shown in the exploded view ofFIG. 9 a as seen from section lines 9 d-9 d in FIG. 9 a.

FIG. 10 is a side elevational assembled view of the embodiment of FIG. 9a.

FIG. 11 is a partial cut-away, three-quarter perspective view of theanchor with a cross section removed so as to clearly see the repositorybore embodiment.

FIG. 12 is a partial cut-away, three-quarter perspective view of theabutment with a cross section removed so as to clearly see the smoothinner surface of the abutment.

FIG. 13 is a side plan view of the anchor shown in FIG. 11.

FIG. 14 is a side longitudinal cross sectional view of the assembledanchor and abutment coupled together via a threaded bolt.

The invention and its various embodiments can now be better understoodby turning to the following detailed description of the preferredembodiments which are presented as illustrated examples of the inventiondefined in the claims. It is expressly understood that the invention asdefined by the claims may be broader than the illustrated embodimentsdescribed below.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Conventional dental implants incorporate screws with standard threadprofiles such as acme threads, buttress threads, or circumferentialgrooves or even holes drilled through the device into which bone maygrow to bind the screw. These implants require regeneration of bone togrow into and around the screw, which can take months, to fully anchor.In addition, conventional implants can weaken the implant site as aresult of occlusal processes because of the radial spreading forcestransferred from the tooth through the screw to the bone by their threaddesigns and groove geometries.

The illustrated embodiments of the invention provide an interlockingmechanism for an implant anchor. Through a “chevron” shaped externalthread geometry on the screw, the implant anchor becomes interlockedwith the receiving hole in the bone immediately upon installation. Thisresults in shorter healing time, simplified procedures, reduced cost andless pain for the patient. The chevron thread not only produces betterresistance to shear loads during the occlusal processes, but also addsstrength to the implant site. These properties lead to better long-termstrength and durability for the implant. The stronger fixation providedby the illustrated embodiments of the invention can produce a betterplatform for the prosthesis in softer portions of the jaw bone such asin molar areas, and may benefit osteoporotic bone as well, which isoften too brittle for standard implants.

FIGS. 2 a-2 d show a dental implant assembly 20 in accordance with anembodiment of the invention. A prosthetic tooth 21 is arranged andconfigured to be mounted on a top post 22 a of an abutment 22. Althoughthe abutment 22 has a generally conical shape to match mating surfacesdefined into tooth 21, the right cylindrical post 22 b forming the topof abutment 22 may have flat vertical facets 22 a as shown in the topview of FIG. 2 b of the abutment 22. This allows a torque to be appliedto the abutment 22 on the flat surfaces 22 a using a wrench or othertool to facilitate screwing abutment 22 into inferior structures inassembly 20 described below.

The abutment 22 has an axial bore 25 a with an internal thread 25, sothat abutment 22 can be threaded onto the external thread 23 a of anexternally-threaded stem 23 of the implant anchor or screw 24 as bestshown in FIG. 6. External threads 23 a are arranged and configured toprovide mechanical coupling of anchor 24 to collar 28 and abutment 22.Chevron threads 24 a are selectively defined in or on the exterior ofanchor 24 from or near the lower end of threads 23 a to or near thedistal end of anchor 24. As shown in FIG. 6, when assembled only chevronthreads 24 a will be exposed to the bone when implant assembly 20 iscompletely assembled as intended. Opposing collar 26 is also providedwith an axial bore 26 c with an internal thread 26 b to screw ontothread 23 a and engage threaded stem 23. Collar 28 can be selectivelyadjusted up or down to aid in the implantation procedure as best shownin FIG. 6. The opposing collar 26 also provides a larger-diametersupport base on stepped surface 28 for firm support of the lower steppedsurface 27 of abutment 22, which is again best depicted in FIG. 6. Thebottom surface 27 of the abutment 22 seats against surface 28 of theopposing collar 26. The opposing collar 26 is tightened onto theexternally-threaded stem 23 through internal threads 26 b, using aspanner wrench applied to holes 26 a defined into surface 28 as bestshown in FIG. 2 c. The implant anchor 24 is tightened into a receivingfemale hole formed by the oral surgeon in the jaw bone, which hole hasthreads matching the external threads 24 a. Tightening is performedusing driving slot 29 defined in the upper end of the implant anchor 24as depicted to top plan view in FIG. 2 d.

A distal threaded portion 30 of the implant anchor 24 in accordance withthe embodiment of FIGS. 2 a-2 d is illustrated in enlarged scale in sideelevational view in FIG. 3. The threaded section 30 has a generallycylindrical shaped envelope with a longitudinal axis 31. The externalthread 24 a is defined helically around the circumference of the section30. The depth of external thread 24 a extends between a minor diameter33 and a major diameter 37 of the threaded section 30.

The external thread 24 a has a first superior contact surface 34 and asecond more radial superior contact surface 35, an interlocking inferiorflank surface 36, and an inferior relief surface 38. When viewed in aside or longitudinal cross-sectional view, the contact surfaces 34 and35 form an approximate “V” shape, with the flank surface 36 and therelief surface 38 also forming an approximate “V” shape. The thread hasan overall “chevron” shape in the cross-sectional view as shown in thepartial cut-away side cross-sectional view in the lower right portion ofFIG. 3.

Interlocking flank surface 36 forms an angle γ, which in accordance withthe embodiment of FIG. 3 is approximately 90 degrees to the axis 31.Contact surface 34 forms an angle α to the axis 31. The angle α istypically greater than the angle γ, e.g., greater than 90 degrees in theembodiment of FIG. 3. The difference between the first and second anglesα and γ, together with the upward-angled surface 35, making an acuteangle θ with respect to axis 31, provide an interlocking interference ofthe male threaded section 30 to a female threaded receiving hole formedby the oral surgeon in the bone.

Pullout of anchor 24 from the bone is prevented as a result of the angleof contact surface 34 relative to the angle of contact surface 35. Amirror shaped thread formed in the bone mates with surfaces 34 and 35 ofanchor 24, so that the mirror surfaces in the bone are juxtapositionedto surfaces 34 and 35 and substantially prevent or limit any radialmovement of anchor 24 relative to the bone. Any attempted radialmovement of anchor 24 would tend to cause the outer portion of thethread 24 a to move downwardly at the angle β due to the overlying boneadjacent to surface 35. However, such movement is blocked ormechanically resisted, because it would tend to drive surface 36 intothe opposing juxtapositioned surface of the bone adjacent to surface 36.Hence, anchor 34 is radially locked into place relative to any radialocclusive forces or other forces having a radial component which may beapplied to anchor 24. Further, the next lower adjacent thread surface 34will tend to support the bony material resisting downwardly drivensurface 36 in the thread above it, thereby providing a strong backing.

FIG. 4 shows a female threaded portion 40 which is formed in the bone.The female thread teeth 43 are complimentarily shaped to the male thread24 a, and have surfaces 41 and 42 corresponding to surfaces 34 and 35,respectively. The female threaded portion 40 of bone is preferablyformed by threading a hole with a tap which is the approximate mirrorshape the male threads 24 a. In the illustrated embodiment, anchor 24 isnot self-tapping and hence no substantial radially compressive forcesare normally applied to the bone when a pure torque is applied to anchor24. However, it must be understood that it is entirely within the spiritand scope of the invention that threads 24 a could be modified to assumea self-tapping form if desired.

FIG. 5 is a side elevational view of the male threaded portion 30 ofFIG. 3 engaged with a side cross-sectional view of the female threadedportion 40 of bone with a partially cut-away section of the anchor 24shown in side cross-sectional view. In such an engaged state, aninterlocking joint is created as described above. As the connectionbetween the male threaded portion 30 and the female threaded portion 40is tightened, surfaces 34 and 35 bear against surfaces 41 and 42,respectively. A centering force is generated between the female threadedportion 40 and the male threaded portion 30 because of the chevronshape. This centering force is uniformly and helically distributedaround the circumference of the mating threads when engaged. Thiscentering force prevents spreading or drawing of the joint between theanchor 24 and the threaded hole in the bone.

A vector reactive force from the bone illustrated as arrow 51 in FIG. 5acts upon the contact surface 34 of thread 24 a by surface 41 of thetapped bone, and a vector reactive force from the bone illustrated asarrow 52 acts upon the surface 38 of thread 24 a by means of surface 44of the tapped bone. Both vector forces 51 and 52 have an inward radialcomponent toward the axis 31, which radial component is determined bythe angle of the reactive surfaces and their areas. Similarly, areactive vector force from the bone represented by arrow 53 acts uponthe contact surface 35 of thread 24 a by surface 42 of the tapped boneand has an outward radial component away from the axis 31. The vectorsum forces 51, 52 and 53 prevent the threaded portion 30 of anchor 24from radially sliding with respect to the female threaded portion 40 ofthe tapped bone, or provide a net centering force.

FIG. 6 shows the assembled device 20 with the opposing collar 26overlying the threads 24 a of the implant anchor 24. When tightened, thedownward-angled surface 26 c of the opposing collar 26 creates areaction force from the bone which opposes the reaction force from thebone arising from upward-angled thread 24 a, thereby creating alongitudinal clamping force.

FIGS. 7 a-7 d show an opposing collar 70 in accordance with anotherillustrated embodiment of the invention. The embodiment of FIGS. 7 a-7 ddiffers from that of FIGS. 2 a-2 d in that collar 70 has a relativelysmooth inner bore 71 without threading. This allows the abutment 22 toforce the opposing collar 70 downward as it is threaded onto thethreaded portion 23 of the implant anchor 24 creating a clamping forceagainst the bone due to tightening of abutment 22 instead of tighteningof collar 70. The assembled view of this device is shown in FIG. 8.

FIGS. 9 a-9 d are views which show yet another illustrated embodimentwhere the abutment 92 is provided with a male threaded distal shaft 95instead of an internal female threaded portion 25 as in the aboveembodiments. The threaded shaft 95 couples to the implant anchor 24within an axially defined female threaded hole 93. FIG. 10 is a sidecross-sectional view which shows an assembled implant assembly 20 ofFIGS. 9 a-9 d.

FIGS. 11-14 depict an alternative embodiment of the implant anchor andabutment, denoted for this embodiment as references 100 and 108respectively.

As best seen in FIG. 11, the implant anchor 100 comprises a collar 120at its proximal end. The collar 120 further comprises a collar ring 102disposed on the top of the collar 120. The collar ring 102 comprises aplurality of female keyways 104 that are located symmetrically about thecollar ring 102. The keyways 104 depicted are defined as squareindentations, but other shapes, placements or numbers of keyways in thecollar ring 102 here may also be used by the skilled artisan withoutdeparting from the original spirit and scope of the invention. In thepreferred embodiment, anchor 100 is an integral or single piece machinedelement, but may be comprised of joined portions if desired.

Also seen in FIG. 11 is a hollow blind bore defined on the longitudinalaxis of the implant anchor 100 with an inner female threaded surface 116that is disposed throughout the bore. At the distal end of the implantanchor 100 is a large elliptical repository bore 106. The repositorybore 106 comprises at least two diametrically opposed openings definedthrough the wall of the implant anchor 100 near the end of the blindbore that are arranged so that a hole or opening is present through theentire diameter of the implant anchor as best seen in FIG. 13. In theillustrated embodiment, repository bore 106 is partially defined throughthe bore and partially defined through the solid lower end portion ofanchor 100 in approximately equal fractions, although placement withrespect to the bore is not critical. However, it can be seen that it isadvantageous to have repository bore 106 begin in the wall of anchor 100at approximately the lowest level of the exterior threading so that chiprelief is available into repository bore 106 at or near where bonecutting by the exterior threading will first occur. Repository bore 106renders the implant anchor 100 self-tapping when being inserted into thebone of a patient, because bone material that has been removed or cut bythe external threads of the implant anchor 100, is removed from orclears the threads and enters the implant anchor 100 through therepository bore 106 as the anchor 100 is being turned into the bone.This process then clears the bone debris away from the threads of theimplant anchor 100 and stores it within the anchor 100 itself, thuslowering the probability of any bone debris becoming stuck or jammedwithin the threads of the device and preventing possible galling. Therepository bore 106 is defined as elliptical openings in FIGS. 11, 13,and 14, however it is to be expressly understood that fewer oradditional openings or other shapes others than those shown may be usedby the skilled artisan without departing from the original spirit andscope of the invention.

In FIG. 12, an alternative embodiment of the abutment 108 is shown. Theabutment 108 comprises a recessed inner flange 110 disposed on itsdistal or lower end. The inner flange 110 further comprises a pluralityof male keys 112 located symmetrically around the inner flange 110. Thekeys 112 depicted are of a square shape to match and easily slip intothe keyways 104 defined in collar ring 102, but other shapes or numbersof pegs in the inner flange 110 not shown here may also be used by theskilled artisan without departing from the original spirit and scope ofthe invention. Additionally, the abutment 108 comprises a hollow bore118 defined through its longitudinal axis with a smooth inner surfacethroughout as seen in FIG. 12. Bore 118 provides a clearance hole for abolt which secures abutment 108 to anchor 100 as described below inconnection with FIG. 14.

The abutment 108 couples to the implant anchor 108 via the male keys 112disposed on the inner flange 110 of the abutment 108 and the femalekeyways 104 disposed on the collar ring 102 of the implant anchor 100 tocreate an anti-rotation lock which prevents abutment 108 from rotatingwith respect to anchor 100 after it is secured thereto. As is known inthe art, abutment 108 need not be a straight cylinder as shown in FIG.12, but may include a variety of inclined or angled shapes. A dentalcrown or other dental appliance (not shown) will later be attached toabutment 108 and in the event that the receiving bore in the jaw has notbeen perfectly drilled at the correct angle, the angular misalignment ofanchor 100 in the jaw may be compensated by selecting an abutment 108 ofapproximately equal inclination and then setting the inclined abutment108 at the correct compensating azimuthal position on anchor 100 toeffectively take out the angular misalignment of anchor 100. The numberand spacing of keys 112 and keyways 104 are such to allow a plurality ofmechanically strong, but finely adjustable relative azimuthal settingsbetween anchor 100 and abutment 108 when the two elements are assembledtogether and then mechanically secured together by bolt 114. The dentalcrown or other dental appliance will then be provided with a anangularly oriented abutment 108 for affixation, which is angularlyoriented with respect to the surrounding teeth and dental structures asif the receiving bore for anchor 100 had been perfectly and correctlydrilled. Including an adjustable, positive, mechanical, anti-rotationlock between abutment 108 and anchor 100 is advantageous for securingthis relative angular orientation between abutment 108 and anchor 100 atall later times notwithstanding forces with may be applied to the crownor dental appliance which may tend to disturb its initial angular set inthe jaw.

First, after the implant anchor 100 has been successfully inserted intothe patient's bone, the user lines up the male keys 112 of the abutment108 with the female keyways 104 of the anchor 100 and then inserts thekeys 112 into the keyways 104 until the inner ring 108 is flush againstthe collar ring 120 as seen in FIG. 14. The keys 112 are arranged on theabutment 108 such that the abutment 108 will not be capable of beingpressed flush against the anchor 100 until every key 112 has beencorrectly inserted into its corresponding keyway 104. Once the abutment108 is firmly coupled to the proximal end of the anchor 100, a threadedbolt 114 is inserted through the top of the abutment 108. The bolt 114is pushed through the smooth inner surface 118 of the abutment 108 untilmeeting the interior threading 116 defined in anchor 100. Once in theanchor 100, the threaded bolt 114 engages the inner female threading 116of the implant anchor 100 as seen in FIG. 14. The bolt 114 is threadedor tightened down the longitudinal axis of the implant anchor 100 butits lower end is stopped before overlapping the opening of repositorybore 106 when the head 122 of the threaded bolt 114 meets the innerrecessed surface 124 within the abutment 108. The bolt 114 along withthe coupling of the keys 112 and keyways 104 provides an effective meansfor firmly coupling the abutment 108 to the implant anchor 100 andstrengthening to the overall structure of the device by reducing theprobability of any shifting or loosening of the abutment 108 from theanchor 100 when an off-axis load is applied to the device, for examplewhen the patient is chewing or speaking. The bolt 114 is sufficientlylong enough to extend a predetermined distance into the implant anchor100, but does not extend so far as to block or interfere with theopening of the repository bore 106 and therefore impede the bone debrisclearing process described above.

Many alterations and modifications may be made by those having ordinaryskill in the art without departing from the spirit and scope of theinvention. Therefore, it must be understood that the illustratedembodiment has been set forth only for the purposes of example and thatit should not be taken as limiting the invention as defined by thefollowing invention and its various embodiments. For example, the threadmay not have all of the first contact surface, the second contactsurface, the flank surface, and the relief surface, so long as onesurface, such as the second surface, provides means for preventing thethread from sliding away from the female threaded portion. On the otherhand, more surfaces may be provided. In addition, the surfaces may beangled differently from those shown in the exemplary drawings.

Further although in the illustrated embodiment the keys are defined inthe abutment and the keyways are defined in the anchor, it is entirelywithin the scope of the invention that this choice could be reversed.Namely, the keys could be defined in the anchor and the keyways in theabutment. Therefore, the claims below must be construed to include thenotion that keys and keyways may be reversed with respect to theirposition in the recited elements.

Therefore, it must be understood that the illustrated embodiment hasbeen set forth only for the purposes of example and that it should notbe taken as limiting the invention as defined by the following claims.For example, notwithstanding the fact that the elements of a claim areset forth below in a certain combination, it must be expresslyunderstood that the invention includes other combinations of fewer, moreor different elements, which are disclosed in above even when notinitially claimed in such combinations. A teaching that two elements arecombined in a claimed combination is further to be understood as alsoallowing for a claimed combination in which the two elements are notcombined with each other, but may be used alone or combined in othercombinations. The excision of any disclosed element of the invention isexplicitly contemplated as within the scope of the invention.

The words used in this specification to describe the invention and itsvarious embodiments are to be understood not only in the sense of theircommonly defined meanings, but to include by special definition in thisspecification structure, material or acts beyond the scope of thecommonly defined meanings. Thus if an element can be understood in thecontext of this specification as including more than one meaning, thenits use in a claim must be understood as being generic to all possiblemeanings supported by the specification and by the word itself.

The definitions of the words or elements of the following claims are,therefore, defined in this specification to include not only thecombination of elements which are literally set forth, but allequivalent structure, material or acts for performing substantially thesame function in substantially the same way to obtain substantially thesame result. In this sense it is therefore contemplated that anequivalent substitution of two or more elements may be made for any oneof the elements in the claims below or that a single element may besubstituted for two or more elements in a claim. Although elements maybe described above as acting in certain combinations and even initiallyclaimed as such, it is to be expressly understood that one or moreelements from a claimed combination can in some cases be excised fromthe combination and that the claimed combination may be directed to asubcombination or variation of a subcombination.

Insubstantial changes from the claimed subject matter as viewed by aperson with ordinary skill in the art, now known or later devised, areexpressly contemplated as being equivalently within the scope of theclaims. Therefore, obvious substitutions now or later known to one withordinary skill in the art are defined to be within the scope of thedefined elements.

The claims are thus to be understood to include what is specificallyillustrated and described above, what is conceptionally equivalent, whatcan be obviously substituted and also what essentially incorporates theessential idea of the invention.

We claim:
 1. A method for dispersing forces experienced by a fastenertapped and embedded in a surrounding bone, comprising: negating radiallyoutward spreading forces which would otherwise exist during fastenerinsertion by forming a thread pattern on the fastener drawing thesurrounding bone towards the fastener; negating dynamic loads imposed onthe fastener after embedment by fashioning the thread pattern to offsetloads parallel to a longitudinal axis (31) of the fastener and loads notparallel to the longitudinal axis (31) such that the thread pattern andthe surrounding bone form an interlocking connection there between;wherein the tapped bone having a plurality of surfaces (41, 42) and thethread pattern having a thread (24 a) including a plurality of contactsurfaces (34, 35, 38); and forming complimentary contours on the threadpattern at an interface between the tapped bone and the embeddedfastener such that a vector force (51) having an inward radial componenttoward longitudinal axis (31) exerted by the tapped bone acts upon thecontact surface (34) of the thread by the surface (41) of the tappedbone, a vector reactive force (52) having an inward radial componenttoward longitudinal axis (31) exerted by the tapped bone acts upon thesurface (38) of the thread by means of surface (44) of the tapped bone;and a vector reactive force (53) having an outward radial componenttoward longitudinal axis (31) exerted by the tapped bone acts upon thesurface (35) of the thread by means of surface (42) of the tapped boneto provide a net centering force.